Engine Failure When Performing Boost-Back Burn on Falcon-9 Style 1st Stage Recoveries (Question)

[Sunrax]

I currently am working to make a 1st stage that I can launch a rocket to orbit, boost back, and recover at the KSC. Currently, I play using RSS (not RO), RSS Cape Canaveral, Canaveral Pads, and use Jimbodiah's Simple RSS patch for optimization among about 80 other mods.
 

Whether I use MechJeb2 or do it manually, my engines become unresponsive to throttle control at approx. 30,000 meters (1,200m/s) upon reentry when attempting to land at Cape Canaveral. I've made sure electronics are set, communication to KSC is fine, and the craft is aerodynamically stable, includes the T-222 Nemesis Grid fins for control, and has landing gear. However, no matter what engine(s) I use (stock Vector engines, modded "Micro Mother" engine, Mastodons, 1 engine, multiple engines, etc.), the throttle control of the engines is lost at the previously mentioned altitude and speed.
 

I have deleted all mods that alter any aerodynamic or wind properties, I've messed with reentry heating levels in settings, and I have tried a continuous burn from 70,000m to the 30,000 hard deck. No matter what I do, the engines shut off at this point and are unresponsive when using MechJeb2 or doing it manually. However, all control surfaces and gimble are fine. If I flip the craft on its side and glide it along the Cape for a long time, eventually the engine turns on again at random times (once at 100m @ 154m/s and another time higher and with more speed).
 

Any ideas? I can provide screenshots, logs, or videos if necessary. I've been playing modded KSP for a while now, so this is baffling me. Any help or ideas is appreciated.

[Sunrax]

Solved by a user on the r/kerbalspaceprogram subreddit. The problem was limited Q in MechJeb2 ascent guidance.